Lecture #8: Atypical Bacteria Part 2
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Questions and Answers

What is a potential consequence of untreated infections with the pathogens mentioned?

  • Acute respiratory distress syndrome
  • Chronic fatigue syndrome
  • Severe dehydration
  • Multiple organ failure (correct)
  • Which laboratory findings were observed in the case of the 72-year-old man with human myelocytic ehrlichiosis?

  • Increased hemoglobin and respiratory distress
  • Decreased white cell count and elevated liver function tests (correct)
  • Increased white cell count and kidney function abnormalities
  • Normal hemoglobin and negative Ehrlichia PCR
  • Which of the following clinical manifestations is associated with rickettsial diseases?

  • Muscle rigidity
  • Petchial rash (correct)
  • Nausea and vomiting
  • Erythema migrans
  • What type of bacteria are Ehrlichia species classified as?

    <p>Obligate intracellular bacteria that do not pick up Gram stain</p> Signup and view all the answers

    Which treatment is indicated for infections caused by the pathogens discussed?

    <p>Doxycycline</p> Signup and view all the answers

    What type of organism is primarily responsible for the illness described?

    <p>Bacteria</p> Signup and view all the answers

    How is Rickettsia rickettsii primarily transmitted in nature?

    <p>Transovarial and trans-stadial transmission in ticks</p> Signup and view all the answers

    Where does Rocky Mountain spotted fever (RMSF) occur most commonly?

    <p>Eastern and central US</p> Signup and view all the answers

    What is a key characteristic of the rash associated with RMSF?

    <p>It is petechial and extensive</p> Signup and view all the answers

    What might happen if RMSF is not diagnosed in a patient?

    <p>Severe complications including edema and hypotension</p> Signup and view all the answers

    What initial symptoms indicate a potential RMSF infection?

    <p>Fever over 102F, severe headache, and myalgia</p> Signup and view all the answers

    What cellular mechanism do Rickettsia use to spread within the host?

    <p>Hijacking actin filaments for movement</p> Signup and view all the answers

    Which vector species is predominantly associated with RMSF in the eastern and central US?

    <p>Dermacentor variabilis</p> Signup and view all the answers

    What type of bacteria are Rickettsia spp. classified as?

    <p>Obligate intracellular bacteria</p> Signup and view all the answers

    Which type of organism is a frequent endosymbiont of Rickettsia spp.?

    <p>Ticks</p> Signup and view all the answers

    Which of the following diseases is caused by Rickettsia rickettsii?

    <p>Rocky Mountain Spotted Fever</p> Signup and view all the answers

    How are Rickettsial infections primarily transmitted?

    <p>Bite of infected arthropods</p> Signup and view all the answers

    What characteristic of Rickettsia spp. makes them unique in terms of staining?

    <p>They do not Gram stain but have a Gram-negative cell wall.</p> Signup and view all the answers

    Which of the following is NOT a method of preventing Rickettsial infections?

    <p>Use of vaccines</p> Signup and view all the answers

    Which symptom is NOT typically associated with Rickettsial diseases?

    <p>Persistent dry cough</p> Signup and view all the answers

    In which human cells do Rickettsia often replicate?

    <p>Endothelial cells</p> Signup and view all the answers

    What is the initial site of the rash associated with RMSF?

    <p>Ankles and wrists</p> Signup and view all the answers

    Which of the following statements about the progression of RMSF is true?

    <p>Vascular injury can lead to multiple system damages.</p> Signup and view all the answers

    Which diagnostic method is utilized within the first week of RMSF symptom onset?

    <p>PCR</p> Signup and view all the answers

    What is the case fatality rate for untreated RMSF patients?

    <p>30%</p> Signup and view all the answers

    What is the causative agent of Epidemic Typhus?

    <p>Rickettsia prowazekii</p> Signup and view all the answers

    What is the primary reservoir for Endemic Typhus?

    <p>Rats and opossums</p> Signup and view all the answers

    Which treatment is common for both Epidemic and Endemic Typhus?

    <p>Doxycycline</p> Signup and view all the answers

    What vector is associated with Scrub Typhus?

    <p>Trombiculid mites</p> Signup and view all the answers

    What is the primary reservoir for the pathogen causing Ehrlichiosis?

    <p>White-tailed deer</p> Signup and view all the answers

    Which vector is associated with the transmission of Ehrlichiosis?

    <p>Amblyomma americanum</p> Signup and view all the answers

    Which laboratory finding is commonly associated with Ehrlichiosis?

    <p>Leukopenia</p> Signup and view all the answers

    What is the primary treatment for Ehrlichiosis?

    <p>Doxycycline</p> Signup and view all the answers

    Which symptom is NOT typically associated with Ehrlichiosis?

    <p>Nasal congestion</p> Signup and view all the answers

    What process does the pathogen use to infect monocytes and macrophages during Ehrlichiosis?

    <p>Phagocytosis induction</p> Signup and view all the answers

    How does the Ehrlichiosis pathogen primarily exit the host cell?

    <p>Cell lysis or exocytosis</p> Signup and view all the answers

    What diagnostic method was used to confirm the diagnosis of Ehrlichiosis in the case presented?

    <p>PCR of blood</p> Signup and view all the answers

    What is the primary pathogen responsible for Anaplasmosis?

    <p>Anaplasma phagocytophilum</p> Signup and view all the answers

    Which vector is primarily responsible for the spread of Anaplasma?

    <p>Ixodes scapularis</p> Signup and view all the answers

    What type of cells do Anaplasma primarily infect?

    <p>Neutrophils</p> Signup and view all the answers

    What is a common diagnostic finding for Anaplasmosis?

    <p>Presence of morulae in cytoplasm of neutrophils</p> Signup and view all the answers

    Which of the following is a frequent laboratory abnormality seen in Anaplasmosis?

    <p>Thrombocytopenia</p> Signup and view all the answers

    What is the primary treatment for Anaplasmosis?

    <p>Doxycycline</p> Signup and view all the answers

    Which part of the body commonly has the greatest burden of Anaplasma infection?

    <p>Liver</p> Signup and view all the answers

    What major risk factor is associated with Anaplasmosis infections?

    <p>Tick bites from infected Ixodes scapularis</p> Signup and view all the answers

    Study Notes

    Atypical Bacteria: Rickettsiales

    • Rickettsiales are obligate intracellular bacteria
    • They are frequent endosymbionts of ticks
    • They are often found in endothelial cells
    • They do not gram stain, but have gram-negative cell walls
    • They are transmitted by ticks and other blood-sucking arthropods
    • Different rickettsial diseases discussed include Spotted Fever, Epidemic Typhus, Endemic Typhus, Scrub Typhus, Anaplasmosis, and Ehrlichiosis

    Rickettsial Diseases

    • Rocky Mountain Spotted Fever (RMSF):

      • Agent: Rickettsia rickettsii
      • Vector: Dermacentor variabilis (ticks)
      • Reservoir: rodents
      • Incubation period: 3-12 days
      • Symptoms: fever, headache, chills, myalgia, nausea, vomiting, rash (begins on extremities, spreads to palms and soles)
      • Diagnostic tests: PCR, serology (antibody titer)
      • Treatment: doxycycline
    • Epidemic Typhus (Louse-borne Typhus):

      • Agent: Rickettsia prowazekii
      • Vector: human body louse
      • Reservoir: humans
      • Symptoms: high fever, headache, chills, myalgia, rash
      • Diagnostic tests: PCR, serology
      • Treatment: doxycycline
    • Endemic Typhus (Flea-borne Typhus):

      • Agent: Rickettsia typhi
      • Vector: fleas
      • Reservoirs: rodents, cats, opossums
      • Symptoms: high fever, headache, chills, myalgia, rash
      • Diagnostic tests: PCR, serology
      • Treatment: doxycycline
    • Scrub Typhus:

      • Agent: Orientia tsutsugamushi
      • Vector: mites (chiggers)
      • Reservoir: rodents
      • Symptoms: high fever, severe headache, chills, myalgia, rash
      • Treatment: doxycycline
    • Anaplasmosis:

      • Agent: Anaplasma phagocytophilum
      • Vector: ticks (Ixodes scapularis)
      • Reservoir: deer, other mammals
      • Symptoms: fever, headache, chills, myalgia, thrombocytopenia, leukopenia, anemia
      • Diagnosis: PCR, serology
      • Treatment: doxycycline
    • Ehrlichiosis:

      • Agent: Ehrlichia chaffeensis
      • Vector: ticks (Amblyomma americanum, Rhipicephalus sanguineus)
      • Reservoir: deer, other mammals
      • Symptoms: fever, headache, chills, myalgia
      • Diagnosis: PCR, serology
      • Treatment: doxycycline

    General Characteristics of Rickettsiae

    • Obligate intracellular bacteria
    • Do not gram stain but have a gram-negative cell wall
    • Multiply within host cells, causing damage to those cells and to blood vessels.

    Other Relevant Info

    • Clinical manifestations usually include fever, headache, myalgia, rash (in some cases), and other symptoms.
    • Diagnostic methods are often PCR tests or antibody tests.
    • Treatment in most cases is doxycycline.

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    Atypical Bacteria 2 2024 PDF

    Description

    Test your knowledge on rickettsial and ehrlichial infections, including their transmission, symptoms, and treatment options. This quiz covers various aspects of these diseases, including laboratory findings and the characteristics of the pathogens involved. Challenge yourself and learn more about these important infectious diseases.

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